Method and apparatus for selecting a location platform for a user equipment to roam and method for determining a location of a user equipment using the same

ABSTRACT

A method and an apparatus for selecting a location platform for a user equipment to roam and a method for determining the location of the user equipment using the same. The method for selecting a location platform includes: checking a visiting network of the UE in response to a location request message transmitted from the UE which is roaming; and selecting a location platform to calculate a location of the UE by comparing positioning capability information of the checked visiting network and positioning capability information of a home network of the UE. According to such a method, it is possible to efficiently perform the positioning of the UE, regardless of the location of the UE, thereby improving the quality of the positioning service.

PRIORITY

This application claims to the benefit under 35 U.S.C. 119(a) of anapplication entitled “Method and Apparatus for Selecting LocationPlatform for User Equipment to Roam and Method for Determining Locationof User Equipment using The Same” filed in the Korean IntellectualProperty Office on May 17, 2004 and assigned Serial No. 2004-34608, theentire contents of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a mobile communicationsystem, and more particularly to an apparatus and a method fordetermining a location of a user equipment (UE).

2. Description of the Related Art

Recently, the wide spread use of UEs has expanded throughout the world.Further, in a global mobile communication system, many users want toreceive application services (e.g., traffic, daily information, etc.)using location information of UEs equipments. Accordingly, user locationinformation acquisition systems using UEs have been commercialized insome countries and mobile communication network areas (e.g., SK telecomand KTF in Korean mobile communication network area, and NTT, DoCoMo,Sprint PCS, KDDI, Vodafone in Japan and Western mobile communicationnetwork areas).

In order to provide application services using location information, itis necessary to determine a location of a UE in advance. That is, theapplication services using location information are created on the basisof geographical position information of a UE, which is determined fromthe location of the UE.

In order to acquire the geographical position information of a UE, theUE must receive a positioning service, regardless of the location of theUE. That is, the UE must receive the positioning service, regardless ofwhether the UE is located in a home area or a roaming area.

The positioning service is provided by a location platform (LP)contained in a network. For example, a home location platform (HLP)contained in a home network or a visiting location platform (VLP)contained in a roaming network provides auxiliary location information(e.g., auxiliary GPS information) to the UE or performs a locationcalculation using information received from the UE, in order to providethe positioning service.

The location of a UE in the mobile communication network can bedetermined by various ways, including three representative examples,which will be described below.

First, the location of a UE can be determined for each cell by usinginformation of the cell nearest to the location of the UE or by usinginformation of the cell managing the UE.

Second, the location of a UE can be determined based on the network. Inthis network-based positioning, intensity of transmission and receptionsignals between a node B (or base station), a UE a time-of-arrival (TOA)of a radio wave signal transmitted from the node B to the UE, or atime-difference-of-arrival (TDOA) of a radio wave signal between the UEeach of multiple node Bs is calculated. Thereafter, triangulation isperformed using the TOA or TDOA, in order to determine the location ofthe UE.

Third, the location of a UE can be determined by using a globalpositioning system (GPS) developed by the U.S. Department of Defense.

From among the above-described positioning schemes, the positioningscheme using the GPS is employed in the mobile communication networktogether with supplementation of the GPS technique. Such a positioningscheme using a supplemented GPS is called a network assisted GPS(NA-GPS). The NA-GPS transmits auxiliary GPS information, which isnecessary to determine the location of a UE using a network(particularly, using the mobile communication network), to the UE,thereby shortening the time-to-first-fix (TTFF) of the UE.

The auxiliary GPS information transmitted to the UE in a networkincludes satellite IDs of the respective satellites, almanac data,satellite orbit information, a clock error correction value, anionosphere correction value, a differential GPS (DGPS) correction value,and a list of invisible satellites. The almanac data is locationinformation (e.g., a model) of a satellite according to time sectionsfor a predetermined time period, which is used to detect an approximatelocation of the satellite, particularly to distinguish a visiblesatellite. The satellite orbit information and the clock errorcorrection value are information for providing an accurate model of asatellite location to a UE. The ionosphere correction value is used tocorrect an ionosphere delay error, which occurs when a radio signalpasses through an ionosphere contained in a pseudo distance between asatellite and a UE, by about 50%. The ionosphere correction valuechanges slower than other information.

The DGPS correction value improves the accuracy of a UE location, byenabling a basic node B to calculate and remove a deviation errorcontained in the pseudo distance. The almanac data, the satellite orbitinformation, the clock error correction value, and the DGPS correctionvalue must be determined according to satellites.

FIG. 1 is a block diagram schematically illustrating a conventionalmobile communication system. More specifically, FIG. 1 illustrates amobile location service (MLS) system for determining the location of aUE in a mobile communication network. The mobile communication systemfor determining the location of a UE includes a UE 110, a node B (orbase station) 120, a radio network controller (RNC) 130, a home locationplatform (HLP) 140, a core network (CN) 150 and a mobile locationservice client (MLS client) 160.

The node B 120 transmits a radio wave signal to the UE 110 located in aspecific cell. Also, the node B 120 measures a radio wave signalreceived from the UE 110, and transmits predetermined data (e.g., TODA)required to determine the location of the UE 110 to the RNC 130. In thiscase, a Uu interface is used for communication between the node B 120and the UE 110.

The RNC 130 manages the radio resources of the node B 120, controls aprocedure for determining the location of the UE 110, and performslocation calculation. In this case, an Iub interface is used forcommunication between the RNC 130 and the node B 120.

The HLP 140, which is also called a location platform (or locationserver), provides auxiliary location information to the UE 110, andperforms a location information service by performing locationcalculation and the like. For example, the HLP 140 transmits theauxiliary GPS information to the UE 110, which is one of the auxiliarylocation information, thereby enabling a network-assisted GPS service tobe provided to UEs 110 located in a relevant network.

The CN 150 manages information about the UEs 110 and performs mobilitymanagement, session management, and call management. Accordingly, the CN150 and the RNC 130 communicate with each other using an Iu interface.

The MLS client 160 is connected to the network and provides a service inrelation to locations of the UEs 110. That is, the MLS client 160requests location information of a specific UE 110 from the CN 150 andprovides a location service to the relevant UE 110 using the locationinformation. In this case, the MLS client 160 and the CN 150 communicatewith each other using an Le interface.

In the above-described system of FIG. 1, when the UE 110 is located in ahome network, the UE 110 receives auxiliary location information (e.g.,auxiliary GPS information) from the HLP 140 contained in the homenetwork. The HLP 140 may calculate the location of the UE 110, i.e., thelocation of the UE 110 is determined by the HLP 140.

Referring to FIG. 2, when the UE 110 roams from a home network 100 toanother network 200, i.e., when the UE 110 visits another network 200,the UE 110 may determine the location of the UE 110, by using either avisiting location platform (VLP) 240 contained in the network 200 (inwhich the UE 110 is roaming) or the HLP 140 contained in the homenetwork 100.

However, in order to determine the location of a roaming UE 110 usingthe VLP 240, the VLP 240 must be able to have a positioning capability,such as information about whether or not various positioning schemesaccording to required location accuracy are supported and informationabout whether or not an assisted GPS (A-GPS) scheme in a control planeand a user plane is supported, according to a request of the UE 110, andpersonal location information of the UE 110 must be kept secret.Therefore, when the roaming UE 110 requests auxiliary locationinformation for determining a location in a user-plane A-GPS scheme, thepositioning scheme using the VLP 240 may cause a number of problems.That is, if the VLP 240 supports only a control-plane A-GPS scheme, theVLP 240 cannot provide auxiliary GPS information to the UE 110. Further,there is another problem in that the personal location information ofthe UE 110 is disclosed as soon as the positioning service beginsbetween the VLP 240 and the UE 110.

In order to determine the location of a roaming UE 110 using the HLP140, a regional range where the HLP 140 can provide auxiliary locationinformation (e.g., auxiliary GPS information) must include a visitingarea where the UE 110 is located.

In addition, although the positioning scheme using the HLP 140 has asuperior capability in security and protection of personal locationinformation, the positioning scheme using the HLP 140 has a disadvantagein that the accuracy of auxiliary location information (or auxiliary GPSinformation) is poor, as compared with the case of using the VLP 240.Therefore, in order to improve the quality of the positioning service,it is preferred that the UE 110 selects a location platform inconsideration of both the positioning capability of the HLP 140 or theVLP 240, and capability factors requested by the UE 110, e.g., locationaccuracy, protection of personal location information, security, etc.

However, until now, there has been no such a method capable ofpermitting a roaming UE 110 to select a location platform inconsideration of the above-described positioning capability andcapability factors requested by the UE 110, in order to determine thelocation of the UE 110.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been designed to solve the aboveand other problems occurring in the prior art. An object of the presentinvention is to provide an apparatus and a method for improving thequality of a positioning service, regardless of the location of a userequipment.

Another object of the present invention is to provide an apparatus and amethod for enabling the position of a roaming user equipment to beefficiently determined.

Still another object of the present invention is to provide an apparatusand a method for selecting a location platform in consideration of boththe positioning capability of a location platform and positioningcapability factors requested by a user equipment.

Still another object of the present invention is to provide an apparatusand a method for determining the location of a user equipment using alocation platform, which is selected by the above-mentioned apparatusand method.

To accomplish the above and objects, in accordance with one aspect ofthe present invention, there is provided a method for selecting alocation platform for a user equipment (UE), which is roaming. Themethod includes the steps of: checking a visiting network of the UE inresponse to a location request message transmitted from the UE which isroaming; and selecting a location platform to calculate a location ofthe UE by comparing positioning capability information of the checkedvisiting network and positioning capability information of a homenetwork of the UE.

In accordance with another aspect of the present invention, there isprovided a location platform selection apparatus for a user equipment(UE), wherein the location platform selection apparatus comparespositioning capabilities information of a home location platform of theUE and a visiting location platform in response to a locationinformation request of the UE which is in roaming, and selects alocation platform to calculate a location of the UE. The visitinglocation platform is contained in a visiting network in which the UE isvisiting.

In accordance with still another aspect of the present invention, thereis provided a method for determining a location of a user equipment(UE). The method includes the steps of: checking a visiting network ofthe UE in response to a location request message transmitted from the UEwhich is roaming; selecting a location platform to calculate a locationof the UE by comparing positioning capability information of the checkedvisiting network and positioning capability information of a homenetwork of the UE; acquiring auxiliary information for calculating thelocation of the UE in the selected location platform by exchangingauxiliary location information between the selected location platformand the UE; and calculating the location of the UE using the acquiredauxiliary information.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages of the presentinvention will be more apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram schematically illustrating a conventionalmobile communication system;

FIG. 2 is a block diagram illustrating a roaming state of a userequipment (UE);

FIG. 3 is a block diagram illustrating a system for determining aposition of a roaming UE according to an embodiment of the presentinvention;

FIG. 4 is a flow diagram illustrating a procedure for determining aposition of a UE according to an embodiment of the present invention;

FIG. 5 is a flow diagram illustrating a procedure for determining aposition of a UE according to an embodiment of the present invention;and

FIG. 6 illustrates an example of positioning capability information thatis used as a criterion for selecting a location platform for the a UEaccording to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Preferred embodiments of the present invention will be described indetail herein below with reference to the accompanying drawings. In thefollowing description of the embodiments of the present invention, adetailed description of known functions and configurations incorporatedherein will be omitted when it may obscure the subject matter of thepresent invention.

FIG. 3 is a block diagram illustrating a system for determining aposition of a roaming UE according to an embodiment of the presentinvention. Referring to FIG. 3, the system includes two locationplatforms, i.e., a home location platform (HLP) 140, which is includedin a home network 100 of a UE 110, and a visiting location platform(VLP) 240, which is included in a visiting network 200 of the UE 110.The system manages positioning information of the UEs located in eachnetwork and provides a positioning service. Herein, it is preferred thatthe HLP 140 and the VLP 240 communicate with each other using a roaminglocation protocol (RLP).

The HLP 140 of the home network 100 includes a home-roaming functionunit 141, and the VLP 240 of the visiting network 200 in which the UE110 is roaming includes a visiting-roaming function unit 241. Thehome-roaming function unit 141 and the visiting-roaming function unit241 perform preparatory work for calculating the position of the roamingUE 110 and determine a location platform for performing positioncalculation. That is, the home-roaming function unit 141 compares thepositioning capability of the HLP 140 and the positioning capability ofthe VLP 240, in order to select a location platform to be used for thepositioning service. The visiting-roaming function unit 241 providespositioning capability information of the VLP 240 in response to arequest of the home-roaming function unit 141.

A mobile location service client (MLS client) 160 located out of thenetwork requests position information of the UE 110 to the HLP 140 inthe home network 100. Herein, it is preferred that the MLS client 160and the HLP 140 communicate with each other using a mobile locationprotocol (MLP).

FIG. 4 is a flow diagram illustrating a procedure for determining aposition of the UE 110 according to an embodiment of the presentinvention. More specifically, FIG. 4 illustrates the HLP 140 beingselected as a location platform to provide the positioning service whenthe UE 110 requests information about its own location.

In step S401, the UE 110 in roaming transmits a location request messageto the HLP 140 in order to determine its own location. In this case, thelocation request message is provided to begin a location session and alocation procedure between the HLP 140 and the UE 110. The locationrequest message includes an identifier (MS-ID) of the UE 110,positioning capability information of the UE 110, a specific identifier(location ID) of a cell or an area in which the UE 110 is located, anidentifier (MLS-client-ID) of a service client to perform a servicerequested by the UE 110, etc.

The positioning capability of the UE 110 includes positioning schemessupported by the UE 110. That is, the positioning capability of the UE110 includes characteristics of bearer such as GSM, CDMA, and WLAN,information about a subject to perform location calculation such asMS-Based, MS-Assisted, etc., whether or not a control-plane A-GPS and auser-plane A-GPS are supported.

The HLP 140 having received the location request message checks theidentifier of the UE 110 contained in the location request message, anddetermines if the UE 110 can receive the location service. When it isdetermined that the UE 110 can receive the location service, the HLP 140assigns a new session to the UE 110 in step S403. In step S405, the HLP140 determines the VLP 240 as a location platform with reference to thelocation ID contained in the location request message.

In step S407, the HLP 140 requests information about the positioningcapability of the VLP 240 and conversion of the coordinates (xycoordinates) of the location ID of an area reported by the UE 110, fromthe VLP 240 determined in step S405, using a start roaming locationimmediate request (SRLIR) message of the RLP. The SRLIR message includesa session identifier (ID) of a session assigned in step S403, a locationID, and a positioning capability information request symbol (LPC req.:Location Platform Capability request). In this case, the coordinatesconverted by the request are used in place of the location of a node B.That is, a location platform (LP), which determines the location of theUE 110, generates auxiliary location information using an approximatelocation of the UE 110 (e.g., a location of a node B in which the UE 110is located) and provides the auxiliary location information to the UE110.

In step S409, the VLP 240, having received the SRLIR message in stepS407, responds to the HLP (Home Location Platform) 140 using a startroaming location immediate answer (SRLIA) message of the RLP. The SRLIAmessage includes the session ID, information about a positioningcapability (e.g., LP capability), and approximate coordinate information(e.g., coarse position) of the location ID.

An example of information about the positioning capability (LPcapability) contained in the SRLIA message is illustrated in FIG. 6.However, this information will be described later in more detail withreference to FIG. 6.

The HLP 140, having received the SRLIA message (response message) fromthe VLP 240 in step S409, compares the positioning capability (LPcapability) information of the VLP 240 contained in the SRLIA messagewith positioning capability (LP capability) information of the HLP 140stored in advance in the HLP 140, and selects a location platform toprovide a location information service to the UE 110 in step S411.

For example, when it is possible for the HLP 140 to support theuser-plane A-GPS positioning scheme but it is impossible for the VLP 240to support the user-plane A-GPS positioning scheme, the HLP 140 selectsthe HLP 140 as a location platform. However, when it is impossible forthe HLP 140 to support the user-plane A-GPS positioning scheme but it ispossible for the VLP 240 to support the user-plane A-GPS positioningscheme, the HLP 140 selects the VLP 240 as a location platform. Whenboth of the HLP 140 and the VLP 240 can support the user-plane A-GPSpositioning scheme, the HLP 140 selects one of the HLP 140 and the VLP240 as a location platform, by comparing protection of personal locationinformation, charge, security, positioning capabilities, etc., betweenthe HLP 140 and the VLP 240.

When the HLP 140 already has information about the positioningcapability of the VLP 240, the HLP 140 selects a location platform usingthe already-known positioning capability information. Here, it ispossible to omit the items for the positioning capability informationincluded in the SRLIR and SRLIA messages transmitted in steps S407 andS409.

FIG. 4 illustrates the HLP 140 being selected as a location platform instep S411. Therefore, the HLP 140, having been determined as a locationplatform, calculates the location of the UE 110 using auxiliary locationinformation of the UE 110 in step S413.

Accordingly, the HLP 140 exchanges auxiliary location information withthe UE 110 in step S414. Herein, the HLP 140 acquires auxiliary locationinformation using either an MS-assisted scheme or an MS-based scheme,and calculates the position of the UE 110 using the acquired auxiliarylocation information. The MS-assisted scheme calculates auxiliarylocation information (e.g., estimated value of location) using ameasured value received from the UE 110, and the MS-based schemeacquires an auxiliary location information (e.g., estimated value oflocation) calculated from the UE 110.

After completing the location calculation, the HLP 140 ends the session(e.g., a location session) assigned in step S403 and notifies the UE 110of the end of the session in step S415. Accordingly, the HLP 140transmits a positioning end message to the UE 110, and then the UE 110releases the occupation of all resources, which the UE 110 has occupiedin relation to the location session.

FIG. 5 is a flow diagram illustrating a procedure for determining aposition of a UE 110 according to an embodiment of the presentinvention. More specifically, FIG. 5 illustrates the VLP 240 beingselected as a location platform to provide the positioning service whenthe UE 110 requests information about its own location. However, becausesteps S501 to S511 in FIG. 5 are the same as steps S401 to S411 in FIG.4, the detailed description of steps S501 to S511 will be omitted andthe following description will be made with regard to the stepsfollowing step S511.

Referring to FIG. 5, the HLP 140 determines the VLP 240 as a locationplatform in step S511, and the HLP 140 notifies the relevant VLP 240that the VLP 240 has been determined as a location platform in stepS513. After the HLP 140 notifies the relevant VLP 240 of the locationplatform determination, the HLP 140 receives an acknowledgment signal(ACK) in response to the notification in step S515.

The VLP 240, having received the notification of the location platformdetermination, calculates the location of the UE 110 using auxiliarylocation information of the UE 110 in step S517.

Accordingly, the VLP 240 performs an auxiliary location informationexchange process with the UE 110 via the HLP 140. That is, when the VLP240 requests auxiliary location information the HLP 140 in step S518,the HLP 140 obtains the auxiliary location information through auxiliarylocation information exchange with the UE 110 in step S519 and transmitsthe obtained auxiliary location information to the VLP 240 in step S521.Then, the VLP 240 calculates the location of the UE 110 using theauxiliary location information.

In this case, the VLP 240 acquires auxiliary location information usingeither an MS-assisted scheme or an MS-based scheme, and calculates theposition of the UE 110 using the acquired auxiliary locationinformation. Herein, the MS-assisted scheme calculates auxiliarylocation information (e.g., estimated value of location) using ameasured value received from the UE 110, and the MS-based schemeacquires an auxiliary location information (e.g., estimated value oflocation) calculated from the UE 110.

After the location calculation is completed, the HLP 140 ends thesession (e.g., a location session) assigned in step S503 and notifiesthe UE 110 of the end of the session in step S523. The HLP 140 transmitsa positioning end message (location END message) to the UE 110, and theUE 110 releases the occupation of all resources, which the UE 110 hasoccupied in relation to the location session.

Although the embodiments of the present invention described above withreference to FIGS. 4 and 5 are made with respect to the case in which aUE requests information about its own location, the above-describedprocedures of the present invention can also be used when a networkrequests the location information of a UE. In such a case in which anetwork requests the location information of a UE, there is littledifference except that the subject of location request and the object ofsession end notification change. Therefore, embodiments for the case inwhich a network request the location information of a UE will beomitted.

FIG. 6 illustrates an example of positioning capability information thatis used as a criterion for selecting a location platform for the a UEaccording to an embodiment of the present invention. The positioningcapability information includes a network identifier (ID), a specificidentifier (LP ID) of a location platform, a type of network,information about whether or not a roaming location service issupported, a supported positioning scheme (e.g., a cell ID positioningscheme, a network-based positioning scheme, such as TDOA and the like, aGPS positioning scheme, etc.), a degree of accuracy of each positioningscheme, and information about an A-GPS positioning scheme, whichincludes a kind of supported A-GPS (a control-plane A-GPS or auser-plane A-GPS) and an auxiliary location information generationscheme (MS-based, MS-assisted, etc.).

As described above, according to an embodiment of the present invention,a location platform is selected based on the positioning capability ofthe location platform and positioning capability factors requested by aUE, and the location of the UE is determined using the selected locationplatform. Therefore, the present invention can efficiently perform thepositioning of the UE, regardless of the location of a UE (e.g.,regardless of whether the UE is located in a home area or a roamingarea), thereby improving the quality of the positioning service.

While the present invention has been shown and described with referenceto certain preferred embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the presentinvention as defined by the appended claims. Accordingly, the scope ofthe present invention is not to be limited by the above embodiments, butby the following claims and the equivalents thereof.

What is claimed is:
 1. A method for calculating a location of a userequipment (UE) that is roaming, the method comprising the steps of:receiving, by a home location platform (HLP), a location requestmessage, from the UE, including specific identifier information of anarea in which the UE is located and positioning capability informationincluding positioning schemes which the UE supports; determining, by theHLP having received the location request message from the UE, a visitinglocation platform (VLP) where the UE is located, by referring toinformation included in the location request message, the VLP being alocation platform to calculate the location of the UE; transmitting, bythe HLP, the specific identifier information and the positioningcapability information received from the UE to the VLP; and receiving,by the HLP, the location of the UE calculated from the VLP, the VLPcalculating the location of the UE with the a positioning schemecorresponding to selected from the positioning capability informationreceived from the UE.
 2. The method as claimed in claim 1, furthercomprising: receiving by the HLP, an auxiliary location information fromthe VLP, when the VLP is determined as a location platform, andtransmitting the auxiliary location information to the UE; receiving, bythe HLP, from the UE, the auxiliary location information by exchange ofthe auxiliary location information with the UE, when the VLP is notdetermined as the location platform, and transmitting, to the VLP, theauxiliary location information; and calculating, by the VLP, thelocation of the UE by using the received auxiliary location information.3. The method as claimed in claim 1, wherein one of the HLP and the VLPis selected as the location platform in response to the location requestmessage of the UE.
 4. The method as claimed in claim 3, wherein alocation platform selection apparatus is included in each locationplatform included in networks.
 5. The method as claimed in claim 1,wherein the positioning capability information includes a type ofnetwork, information indicating if a roaming location service issupported, a supported positioning scheme, a degree of accuracy of thepositioning scheme, and an assisted global positioning system (A-GPS)positioning scheme.
 6. The method as claimed in claim 1, furthercomprising notifying the VLP that the VLP is determined as a locationplatform to calculate the location of the UE, when the VLP is selectedas the location platform.
 7. The method as claimed in claim 1, whereinthe VLP determined as the location platform receives the positioningcapability information provided by the UE through the HLP and calculatesthe location of the UE by using the positioning capability information.8. The method as claimed in claim 1, wherein when receiving the locationof the UE calculated from the VLP, the positioning scheme is a MobileStation (MS) assisted scheme represents a scheme of calculatingauxiliary location information using a measured value received from theUE.
 9. The method as claimed in claim 8, wherein the auxiliary locationinformation is related to an auxiliary of Global Positioning System(GPS) information and includes at least one of satellite IDs ofsatellites, almanac data, satellite orbit information, a clock errorcorrection value, an ionosphere correction value, a differential GPScorrection value and a list of invisible satellites.
 10. The method asclaimed in claim 1, wherein when receiving the location of the UEcalculated from the VLP, the positioning scheme is a Mobile Station (MS)based scheme of acquiring auxiliary location information calculated fromthe UE.
 11. The method as claimed in claim 10, wherein the auxiliarylocation information is related to an auxiliary of Global PositioningSystem (GPS) information and includes at least one of satellite IDs ofsatellites, almanac data, satellite orbit information, a clock errorcorrection value, an ionosphere correction value, a differential GPScorrection value and a list of invisible satellites.
 12. The method asclaim in claim 1, wherein the positioning scheme is either a UE-assistedscheme or a UE-based scheme, wherein the UE-assisted scheme is performedby calculating auxiliary location information using a measured valuereceived from the UE, and the UE-based scheme is performed by acquiringauxiliary location information calculated from the UE.
 13. A method forcalculating a location of a user equipment (UE), the method comprisingthe steps of: receiving, by a home location platform (HLP), a locationrequest message including specific identifier information of an area inwhich the UE is located and positioning capability information includingpositioning schemes which the UE supports, the HLP being a locationplatform to calculate a location of the UE; transmitting, by the HLP,the specific identifier information received from the UE to a visitinglocation platform (VLP); receiving, by the HLP, approximate coordinateinformation of the specific identifier information calculated from theVLP; and calculating, by the HLP, the location of the UE with the apositioning scheme corresponding to selected from the positioningcapability information of the UE and the approximate coordinateinformation received from the VLP.
 14. The method as claimed in claim13, wherein one of the HLP and the VLP is selected as the locationplatform in response to the location request message of the UE.
 15. Themethod as claimed in claim 13, wherein the HLP determined as thelocation platform directly receives the positioning capabilityinformation provided by the UE and calculates the location of the UE byusing the received positioning capability information.
 16. The method asclaimed in claim 13, wherein the positioning capability informationincludes a type of network, information indicating if a roaming locationservice is supported, a supported positioning scheme, a degree ofaccuracy of the positioning scheme, and an assisted global positioningsystem (A-GPS) positioning scheme.
 17. The method as claimed in claim13, wherein when receiving the location of the UE calculated by the HLP,the positioning scheme is a Mobile Station (MS) assisted scheme ofcalculating auxiliary location information using a measured valuereceived from the UE.
 18. The method as claimed in claim 17, wherein theauxiliary location information is related to an auxiliary of GlobalPositioning System (GPS) information and includes at least one ofsatellite IDs of satellites, almanac data, satellite orbit information,a clock error correction value, an ionosphere correction value, adifferential GPS correction value and a list of invisible satellites.19. The method as claimed in claim 13, wherein when receiving thelocation of the UE calculated by the HLP, the positioning scheme is an aMobile Station (MS) based scheme, of acquiring auxiliary locationinformation calculated from the UE.
 20. The method as claimed in claim19, wherein the auxiliary location information is related to anauxiliary of Global Positioning System (GPS) information and includes atleast one of satellite IDs of satellites, almanac data, satellite orbitinformation, a clock error correction value, an ionosphere correctionvalue, a differential GPS correction value and a list of invisiblesatellites.
 21. The method as claim in claim 13, wherein the positioningscheme is either a UE-assisted scheme or a UE-based scheme, wherein theUE-assisted scheme is performed by calculating auxiliary locationinformation using a measured value received from the UE, and theUE-based scheme is performed by acquiring auxiliary location informationcalculated from the UE.
 22. A server for calculating a location of auser equipment (UE), the server comprising: a receiver for receivingatransceiver configured to receive a location request message includingspecific identifier information and first positioning capabilityinformation of the UE, from the UE, in order to determine the locationof the UE, receiving a message including positioning capabilityinformation of a visiting location platform (VLP) from the VLP, andreceiving auxiliary location information from the UE; a transmitter fortransmitting a request message requesting positioning capabilityinformation of the VLP to the VLP; and a processor configured todetermine a controller for determining the Visiting Location Platform(VLP) of an area in which the UE is located, based on the locationrequest message, control the transceiver to transmit, to the VLP, arequest message requesting second positioning capability information ofthe VLP, control the transceiver to receive, from the VLP, a messageincluding the second positioning capability information,comparingcompare third positioning capability information of the serverwith the second positioning capability information of the VLP anddetermining, determine one of the VLP and the server having a betterpositioning capability than the other as a location platform (LP), andwhen the server is determined as the LP, exchanging control thetransceiver to exchange auxiliary location information with the UEwithout additional communication with the VLP, and calculating calculatethe location of the UE using the exchanged auxiliary information.
 23. AHome Location Platform (HLP) server for calculating a location of a UserEquipment (UE), the HLP server comprising: a transceiver configured to:receive a location request message from the UE, for starting apositioning session with the UE, wherein the location request messageincludes location identifier information of an area in which the UE islocated, and positioning capability information including a positioningscheme supported by the UE, transmit a request for approximatecoordinate information to the a Visiting Location Platform (VLP),receive the approximate coordinate information from the VLP, exchangeauxiliary location information with the UE; and a processor configuredto establish the positioning session with the UE, wherein the locationof the UE is calculated by the processor of the HLP using the exchangedauxiliary location information, which is received from the UE, and theapproximate coordinate information.
 24. The HLP server as claimed inclaim 23, wherein the positioning scheme includes at least one of aMobile Station (MS)-Assisted scheme and an MS-Based scheme.
 25. The HLPserver as claimed in claim 23, wherein the processor ends thepositioning session with the UE, when the location of the UE iscalculated.
 26. A Home Location Platform (HLP) server for calculating alocation of a User Equipment (UE), the HLP server comprising: atransceiver configured to receive a location request message from the UEfor starting a positioning session with the UE, the location requestmessage including location identifier information of an area in whichthe UE is located and positioning capability information including apositioning scheme which the UE supports, the HLP being a locationplatform to calculate the location of the UE; and a processor configuredto: establish the positioning session with the UE, control thetransceiver to receive auxiliary location information from the UE, andcontrol the transceiver to forward the auxiliary location information tothe VLP in order to calculate the location of the UE, wherein thelocation of the UE is calculated by the VLP using the auxiliary locationinformation and approximate coordinate information obtained in the VLP.27. The HLP server as claimed in claim 26, wherein the positioningscheme includes at least one of a Mobile Station (MS)-Assisted schemeand an MS-Based scheme.
 28. The HLP server as claimed in claim 26,wherein the processor is further configured to end the positioningsession with the UE, when the location of the UE is calculated.